HDV app

[kippard]

What is preferred for 50i HDV, Vegas or Premiere? I was told - is it the case that HDV can't be edited frame specific? (Yes, I'm in the tech quicksand - sorry edDV.)

[edDV]

What is preferred for 50i HDV, Vegas or Premiere? I was told - is it the case that HDV can't be edited frame specific? (Yes, I'm in the tech quicksand - sorry edDV.)

Either can be used for PAL HDV. HDV uses MPeg2 compression.

Your question led me to bring up a PAL HDV project in Vegas 8 for the first time. As you can see, PAL HDV has an I frame (complete frame) every 12 frames. If you cut to I frames that would place a cut about every half second (i.e. 12/25). NTSC HDV places I frames 15 apart so accuracy is also about a half second (i.e. 15/29.97).



The I frame and the next 11 motion compressed frames are called a Group of Pictures (GOP). A GOP can be decompressed back to 12 full frames with computation. It is this computation that makes zeroing onto a specific frame on the timeline difficult or laggy for MPeg compressed projects. Higher compressed MPeg4 is more laggy. High resolution frames add to the processing delays. The decompressed frames go to memory or tmp files. Tmp files add further delay since the disk system runs slower than the CPU and memory.

So, given time you can find a frame and edit to a frame. When you export, new MPeg GOPs are encoded at cut points from the frames stored in the temp files.

Both Premiere Pro CS3 and Vegas 6/7/8 support HDV project timelines.

Does that answer your question?


PS: When you "scrub" the timeline (i.e. pull the marker horizontally over the timeline), at first it will be very laggy as the frames are decompressed to tmp files. When the processing catches up you can "zero-in" with more response. You will also hear your tmp file disk drive labor to keep up with loading the uncompressed frames as you scrub. If the drive is fragmented, you will even hear it scream out loud as it rapidly seeks.

[kippard]

Yes, thanks edDV. Excellent reply (complete with visual aides). I couldn't imagine that it would not be possible, but do remember reading about GOP issues before. The answer - it seems - is yes, but not quickly. I will just have to put up with it. Can I edit with my 1.29GHz, 512 RAM, if I'm willing to tolerate incredible sluggishness, or might it just be un-doable? The m2t file Soopafresh gave me will play with only occasional stutters. Thanks again,

[edDV]

Yes, thanks edDV. Excellent reply (complete with visual aides). I couldn't imagine that it would not be possible, but do remember reading about GOP issues before - they present issues. The answer - it seems - is yes, but not quickly. I will just have to put up with it. Can I edit with my 1.29GHz, 512 RAM, if I'm willing to tolerate incredible sluggishness, or might it just be un-doable? The m2t file Soopafresh gave me will play with only occasional stutters. Thanks again,

That is way too low for HDV. Premiere Pro says 3GHz min. I say it is just adequate with a Core2Duo ~2GHz each and 1GB memory (2GB for Vista).

The way to get around MPeg GOP lags is to recode the MPeg2 to a digital intermediate format like Cineform which is frame based but still compressed. When you edit a Cineform project, the timeline is responsive similar to DV format. This especially becomes important when multiple layers of video are being scrubbed. There is a delay to recode everything to Cineform, but the project flows faster from then on. Cineform files are larger but nothing like working uncompressed.

You can get a Core2Duo Mobo+ CPU + 2GB memory for around $200up if you shop around. You need an upgrade. You'll maybe need a new case + power supply+ low end display card as well so maybe $400-450 for the lot plus software.

[kippard]

I should determine what processor my board can take - maybe I can get the 2GHz, 1GB RAM on my current board. Do you like Windows2000 at all, or stick with XP? Also, am I loosing anything switching to Cineform? Thank you, thank you.

[edDV]

I should determine what processor my board can take - maybe I can get the 2GHz, 1GB RAM on my current board. Do you like Windows2000 at all, or stick with XP? Also, am I loosing anything switching to Cineform? Thank you, thank you.

You should jump ahead to Core2Duo and XP or Vista. These programs need Net Framework 2 and all the DirectShow goodies. Very state of art. Premiere Pro also needs a SS3 CPU, etc.

Cineform (a 1440x1080 limited VFW version) comes with Vegas 6/7/8. There is very low downside other than encoding time and disk space. In exchange you get full frames, improved multigeneration recording and better size scaling. You get better performance and smaller file sizes moving up to Cineform Neo HDV for $250.
http://www.cineform.com/products/NeoHD.htm

I haven't upgraded to NeoHD yet. I will when I get a large enough project to justify the cost or if Cineform needs a tester .

[Soopafresh]

Kippard, you can get a dual or quad core system for cheap these days. It'll be worth it if you're going to be editing on that machine. Your current hardware will be almost impossible to upgrade as it's several generations old.

ed - There's a discount for Cineform Neo HDV if you belong to HV20.com . I think it's $200. Awesome codec - really terrific performance and compression.

There's also an alternative in the $30 Morgan Mjpeg2000 codec, although I haven't tried it yet. Some nice features, including Multi Core processing and 4:4:4 color space. http://www.morgan-multimedia.com/M-JPEG2000/

[Soopafresh]

Did some quick tests. Morgan does a good job of compression but took longer to transcode. Decoding seems really fast - scrubbing through in Premiere seemed fine. Here's a file size comparison:

[edDV]

Thanks for the HV20.com lead Soopafresh.

Hardware MJPEG was the way it was done in the late 90's when CPU's were weak. DV format improved Y performance with a more advanced in frame DCT. For HD, DVCProHD uses four DV hardware processors each processing 1/4 of the picture.

Today's faster CPU processors can do MJPEG for HD in real time.

The Cineform codec is more modern and efficient for a given picture quality. It uses wavelet compression for better up/down scaling and is highly tuned to the latest Intel chips.

[kippard]

Great to read this info. Thank you both. I see the benefit of conversion for scrub and cutting, but what is the color space of HDV and I'm assuming that increasing to 4:4:4 doesn't actually get you more data than you initially record, so what does it help, generations?

[edDV]

Great to read this info. Thank you both. I see the benefit of conversion for scrub and cutting, but what is the color space of HDV and I'm assuming that increasing to 4:4:4 doesn't actually get you more data than you initially record, so what does it help, generations?

HDV is 4:2:0 similar to DVD. While 4:2:0 is fine for 2D distribution it has problems with generation loss and special effects editing because the chroma pixels aren't aligned with luminance pixels.


Graphic from http://www.dvcentral.org/DV-Beta.html

For decode - recode 4:2:0 chroma needs spacial reinterpolation each time and this causes significant loss vs. 4:1:1, 4:2:2 and 4:4:4 where the chroma pixels are aligned with luminance.

For speicial effects editing nothing beats 4:4:4 source. The same filter can be used for each component. Zooms and curves remain aligned in 3D space. In other words, each color component exists at the same 3D coordinate address for a given pixel. This isn't true for 4:2:0. Chroma can drift away from luminance as rounding errors multiply.

Cineform reinterpolates 4:2:0 into 4:2:2 or 4:4:4 for processing. This doesn't sharpen the chroma but it does reduce chroma generation loss when Cineform is decoded and recoded during repeated effects processing.

[kippard]

Nicely explained. I was planning minimal use of effects, probably not even fades. I might desaturate to B&W when I'm working on my post filmic attempts. I want a clean, classic look. Nice to know if I want to do some work in HDV with motion graphics etc. I will probably recode for the other benefits though. Thank you!